Which toilet seat is most comfortable for skinny boney elders while they sit for BM? And which allows more front back access for hygiene?

There’s the flat surface vs the sloped inward surface which I think could allow the butt bones better comfort but I’m not sure. My brother in law is a paramedic and said many seniors gets stuck inside a toilet seat so this is very important. The cushioned ones don’t come with an open front and I think or assume that an open front will allow more area for positioning and washing with the hand sprayer . My parent also has a lower butt bone protruding from muscle loss so I prefer cushioning and am considering simply buying a large sheet of gel foam and making a large wide cover but only found motorcycle seat gel cushions which are 9” . The gel stick on cushions aren’t supportive enough even if I double them. Has anyone found a company that combines elongated cushioned open front toilet seat?